[docs] Update the limitations page
[docs] Update the limitations page

This patch updates the scaling limitations to be a bit more
nuanced.  We have gotten feedback that users think the
limits listed are hard and fast rules and this change is
intended to be more clear about “just works” scale
vs some of the largest scales/configurations that have
been seen/reported.

A community survey will be conducted soon to adjust
these values further.

I also adjusted a few other out of date limitations.

Change-Id: Iafa4f7f3bd9e405f7ffc4e6cde48ec28e6e04081
Reviewed-on: http://gerrit.cloudera.org:8080/13756
Reviewed-by: Andrew Wong <b68e4fdc6430321a6b47400732ff97d7ae91234e@cloudera.com>
Tested-by: Grant Henke <4cf7ebbe638391c4d27a10cf751b99bdbd1a1880@apache.org>

helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu